High-efficiency Wi-Fi (HEW) station and access point (AP) and method for random access contention

ABSTRACT

Embodiments of a high-efficiency Wi-Fi (HEW) station, access point (AP), and method for random access contention in a wireless network are generally described herein. In some embodiments, the HEW station may receive a beacon frame that indicates a number of trigger frames (TFs) included in a beacon interval. The beacon frame may be received from an HEW access point (AP) in channel resources that include multiple sub-channels. The HEW station may receive a random access TF that indicates a random access portion of the sub-channels that are allocated for random access contention during an uplink transmission period. The HEW station may select a candidate sub-channel from the channel resources. When the candidate sub-channel is included in the random access portion, the HEW station may transmit an association request (AR) frame on the candidate sub-channel during the uplink transmission period.

PRIORITY CLAIM

This application claims priority under 35 USC 119(e) to U.S. ProvisionalPatent Application Ser. No. 62/081,630, filed Nov. 19, 2014 which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments pertain to wireless networks. Some embodiments relate towireless local area networks (WLANs) and Wi-Fi networks includingnetworks operating in accordance with the IEEE 802.11 family ofstandards, such as the IEEE 802.11ac standard or the IEEE 802.11ax studygroup (SG) (named DensiFi). Some embodiments relate to high-efficiency(HE) wireless or high-efficiency WLAN or Wi-Fi (HEW) communications.Some embodiments relate to multi-user (MU) multiple-inputmultiple-output (MIMO) communications and orthogonal frequency divisionmultiple access (OFDMA) communication techniques. Some embodimentsrelate to random access contention techniques.

BACKGROUND

Wireless communications has been evolving toward ever increasing datarates (e.g., from IEEE 802.11a/g to IEEE 802.11n to IEEE 802.11ac). Inhigh-density deployment situations, overall system efficiency may becomemore important than higher data rates. For example, in high-densityhotspot and cellular offloading scenarios, many devices competing forthe wireless medium may have low to moderate data rate requirements(with respect to the very high data rates of IEEE 802.11ac). Arecently-formed study group for Wi-Fi evolution referred to as the IEEE802.11 High Efficiency WLAN (HEW) study group (SG) (i.e., IEEE 802.11ax)is addressing these high-density deployment scenarios.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a High Efficiency Wi-Fi (HEW) network in accordancewith some embodiments;

FIG. 2 illustrates an HEW device in accordance with some embodiments;

FIG. 3 illustrates the operation of a method of random access contentionin accordance with some embodiments;

FIG. 4 illustrates an example of a random access scenario that includesmultiple HEW stations in accordance with some embodiments;

FIG. 5 illustrates another example of a random access scenario thatincludes multiple HEW stations in accordance with some embodiments;

FIG. 6 illustrates another example of a random access scenario thatincludes multiple HEW stations in accordance with some embodiments;

FIG. 7 illustrates another example of a random access scenario thatincludes multiple HEW stations in accordance with some embodiments;

FIG. 8 illustrates an example of a random access scenario that includesmultiple random access phases in accordance with some embodiments; and

FIG. 9 illustrates the operation of another method of random accesscontention in accordance with some embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1 illustrates a High Efficiency (HE) Wi-Fi (HEW) network inaccordance with some embodiments. HEW network 100 may include a masterstation (STA) 102, a plurality of HEW stations 104 (HEW devices), and aplurality of legacy stations 106 (legacy devices). The master station102 may be arranged to communicate with the HEW stations 104 and thelegacy stations 106 in accordance with one or more of the IEEE 802.11standards. In accordance with some HEW embodiments, an access point mayoperate as the master station 102 and may be arranged to contend for awireless medium (e.g., during a contention period) to receive exclusivecontrol of the medium for an HEW control period (i.e., a transmissionopportunity (TXOP)). The master station 102 may, for example, transmit amaster-sync or control transmission at the beginning of the HEW controlperiod to indicate, among other things, which HEW stations 104 arescheduled for communication during the HEW control period. During theHEW control period, the scheduled HEW stations 104 may communicate withthe master station 102 in accordance with a non-contention basedmultiple access technique. This is unlike conventional Wi-Ficommunications in which devices communicate in accordance with acontention-based communication technique, rather than a non-contentionbased multiple access technique. During the HEW control period, themaster station 102 may communicate with HEW stations 104 using one ormore HEW frames. During the HEW control period, legacy stations 106 mayrefrain from communicating. In some embodiments, the master-synctransmission may be referred to as a control and schedule transmission.

In some embodiments, the HEW AP 102 may transmit a beacon frame thatindicates a number of trigger frames (TFs) included in a beaconinterval. The HEW station 104 may receive the beacon frame and maytransmit an association request (AR) frame or other uplink frame on aselected candidate sub-channel when the candidate sub-channel isincluded in a random access portion of channel resources. Theseembodiments will be described in more detail below.

In some embodiments, the multiple-access technique used during the HEWcontrol period may be a scheduled orthogonal frequency division multipleaccess (OFDMA) technique, although this is not a requirement. In someembodiments, the multiple access technique may be a time-divisionmultiple access (TDMA) technique or a frequency division multiple access(FDMA) technique. In some embodiments, the multiple access technique maybe a space-division multiple access (SDMA) technique including amulti-user (MU) multiple-input multiple-output (MIMO) (MU-MIMO)technique. These multiple-access techniques used during the HEW controlperiod may be configured for uplink or downlink data communications.

The master station 102 may also communicate with legacy stations 106 inaccordance with legacy IEEE 802.11 communication techniques. In someembodiments, the master station 102 may also be configurable communicatewith the HEW stations 104 outside the HEW control period in accordancewith legacy IEEE 802.11 communication techniques, although this is not arequirement.

In some embodiments, the HEW communications during the control periodmay be configurable to use one of 20 MHz, 40 MHz, or 80 MHz contiguousbandwidths or an 80+80 MHz (160 MHz) non-contiguous bandwidth. In someembodiments, a 320 MHz channel width may be used. In some embodiments,subchannel bandwidths less than 20 MHz may also be used. In theseembodiments, each channel or subchannel of an HEW communication may beconfigured for transmitting a number of spatial streams.

In accordance with embodiments, a master station 102 and/or HEW stations104 may generate an HEW packet in accordance with a short preambleformat or a long preamble format. The HEW packet may comprise a legacysignal field (L-SIG) followed by one or more high-efficiency (HE) signalfields (HE-SIG) and an HE long-training field (HE-LTF). For the shortpreamble format, the fields may be configured for shorter-delay spreadchannels. For the long preamble format, the fields may be configured forlonger-delay spread channels. These embodiments are described in moredetail below. It should be noted that the terms “HEW” and “HE” may beused interchangeably and both terms may refer to high-efficiency Wi-Fioperation.

FIG. 2 illustrates an HEW device in accordance with some embodiments.HEW device 200 may be an HEW compliant device that may be arranged tocommunicate with one or more other HEW devices, such as HEW stationsand/or a master station, as well as communicate with legacy devices. HEWdevice 200 may be suitable for operating as master station or an HEWstation. In accordance with embodiments, HEW device 200 may include,among other things, physical layer (PHY) circuitry 202 and medium-accesscontrol layer circuitry (MAC) 204. PHY 202 and MAC 204 may be HEWcompliant layers and may also be compliant with one or more legacy IEEE802.11 standards. PHY 202 may be arranged to transmit HEW frames. HEWdevice 200 may also include other processing circuitry 206 and memory208 configured to perform the various operations described herein.

In accordance with some embodiments, the MAC 204 may be arranged tocontend for a wireless medium during a contention period to receivecontrol of the medium for the HEW control period and configure an HEWframe. The PHY 202 may be arranged to transmit the HEW frame asdiscussed above. The PHY 202 may also be arranged to receive an HEWframe from HEW stations. MAC 204 may also be arranged to performtransmitting and receiving operations through the PHY 202. The PHY 202may include circuitry for modulation/demodulation, upconversion and/ordownconversion, filtering, amplification, etc. In some embodiments, theprocessing circuitry 206 may include one or more processors. In someembodiments, two or more antennas may be coupled to the physical layercircuitry arranged for sending and receiving signals includingtransmission of the HEW frame. The memory 208 may store information forconfiguring the processing circuitry 206 to perform operations forconfiguring and transmitting HEW frames and performing the variousoperations described herein.

In some embodiments, the HEW device 200 may be configured to communicateusing OFDM communication signals over a multicarrier communicationchannel. In some embodiments, HEW device 200 may be configured toreceive signals in accordance with specific communication standards,such as the Institute of Electrical and Electronics Engineers (IEEE)standards including IEEE 802.11-2012, 802.11n-2009 and/or 802.11ac-2013standards and/or proposed specifications for WLANs including proposedHEW standards, although the scope of the invention is not limited inthis respect as they may also be suitable to transmit and/or receivecommunications in accordance with other techniques and standards. Insome other embodiments, HEW device 200 may be configured to receivesignals that were transmitted using one or more other modulationtechniques such as spread spectrum modulation (e.g., direct sequencecode division multiple access (DS-CDMA) and/or frequency hopping codedivision multiple access (FH-CDMA)), time-division multiplexing (TDM)modulation, and/or frequency-division multiplexing (FDM) modulation,although the scope of the embodiments is not limited in this respect.

In some embodiments, HEW device 200 may be part of a portable wirelesscommunication device, such as a personal digital assistant (PDA), alaptop or portable computer with wireless communication capability, aweb tablet, a wireless telephone or smartphone, a wireless headset, apager, an instant messaging device, a digital camera, an access point, atelevision, a wearable device such as a medical device (e.g., a heartrate monitor, a blood pressure monitor, etc.), or other device that mayreceive and/or transmit information wirelessly. In some embodiments, HEWdevice 200 may include one or more of a keyboard, a display, anon-volatile memory port, multiple antennas, a graphics processor, anapplication processor, speakers, and other mobile device elements. Thedisplay may be an LCD screen including a touch screen.

The antennas 201 of HEW device 200 may comprise one or more directionalor omnidirectional antennas, including, for example, dipole antennas,monopole antennas, patch antennas, loop antennas, microstrip antennas orother types of antennas suitable for transmission of RF signals. In somemultiple-input multiple-output (MIMO) embodiments, the antennas 201 maybe effectively separated to take advantage of spatial diversity and thedifferent channel characteristics that may result between each ofantennas and the antennas of a transmitting station.

Although HEW device 200 is illustrated as having several separatefunctional elements, one or more of the functional elements may becombined and may be implemented by combinations of software-configuredelements, such as processing elements including digital signalprocessors (DSPs), and/or other hardware elements. For example, someelements may comprise one or more microprocessors, DSPs,field-programmable gate arrays (FPGAs), application specific integratedcircuits (ASICs), radio-frequency integrated circuits (RFICs) andcombinations of various hardware and logic circuitry for performing atleast the functions described herein. In some embodiments, thefunctional elements of HEW device 200 may refer to one or more processesoperating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

Embodiments disclosed herein provide two preamble formats for HighEfficiency (HE) Wireless LAN standards specification that is underdevelopment in the IEEE Task Group 11ax (TGax).

In accordance with embodiments, the HEW station 104 may receive a beaconframe that indicates a number of trigger frames (TFs) included in abeacon interval. The beacon frame may be received from the HEW AP 102 inchannel resources that include multiple sub-channels. The HEW station104 may receive a random access TF that indicates a random accessportion of the sub-channels that are allocated for random accesscontention during an uplink transmission period. The HEW station 104 mayselect a candidate sub-channel from the channel resources. When thecandidate sub-channel is included in the random access portion, the HEWstation 104 may transmit an association request (AR) frame or otheruplink frame on the candidate sub-channel during the uplink transmissionperiod. These embodiments will be described in more detail below.

In some embodiments, the channel resources may be used for downlinktransmission by the HEW AP 102 and for uplink transmissions by the HEWstations 104. That is, a time-division duplex (TDD) format may be used.In some cases, the channel resources may include multiple channels, suchas the 20 MHz channels previously described. The channels may includemultiple sub-channels or may be divided into multiple sub-channels forthe uplink transmissions to accommodate multiple access for multiple HEWstations 104. The downlink transmissions may or may not utilize the sameformat.

In some embodiments, the downlink sub-channels may comprise apredetermined bandwidth. As a non-limiting example, the sub-channels mayeach span 2.03125 MHz, the channel may span 20 MHz, and the channel mayinclude eight or nine sub-channels. Although reference may be made to asub-channel of 2.03125 MHz for illustrative purposes, embodiments arenot limited to this example value, and any suitable frequency span forthe sub-channels may be used. In some embodiments, the frequency spanfor the sub-channel may be based on a value included in an 802.11standard (such as 802.11ax), a 3GPP standard or other standard.

In some embodiments, the sub-channels may comprise multiplesub-carriers. Although not limited as such, the sub-carriers may be usedfor transmission and/or reception of OFDM or OFDMA signals. As anexample, each sub-channel may include a group of contiguous sub-carriersspaced apart by a pre-determined sub-carrier spacing. As anotherexample, each sub-channel may include a group of non-contiguoussub-carriers. That is, the channel may be divided into a set ofcontiguous sub-carriers spaced apart by the pre-determined sub-carrierspacing, and each sub-channel may include a distributed or interleavedsubset of those sub-carriers. The sub-carrier spacing may take a valuesuch as 78.125 kHz, 312.5 kHz or 15 kHz, although these example valuesare not limiting. Other suitable values that may or may not be part ofan 802.11 or 3GPP standard or other standard may also be used in somecases. As an example, for a 78.125 kHz sub-carrier spacing, asub-channel may comprise 26 contiguous sub-carriers or a bandwidth of2.03125 MHz.

FIG. 3 illustrates the operation of a method of random access contentionin accordance with some embodiments. It is important to note thatembodiments of the method 300 may include additional or even feweroperations or processes in comparison to what is illustrated in FIG. 3.In addition, embodiments of the method 300 are not necessarily limitedto the chronological order that is shown in FIG. 3. In describing themethod 300, reference may be made to FIGS. 1-2 and 4-9, although it isunderstood that the method 300 may be practiced with any other suitablesystems, interfaces and components.

In addition, while the method 300 and other methods described herein mayrefer to HEW stations 104 and HEW APs 102 operating in accordance with802.11 or other standards, embodiments of those methods are not limitedto just those HEW stations 104 or HEW APs 102 and may also be practicedon other mobile devices, such as a user station (STA), an Evolved Node-B(eNB) or User Equipment (UE). The method 300 and other methods describedherein may also be practiced by wireless devices configured to operatein other suitable types of wireless communication systems, includingsystems configured to operate according to various Third GenerationPartnership Project (3GPP) Long Term Evolution (LTE) standards.

At operation 305 of the method 300, the HEW station 104 may receive abeacon frame. In some embodiments, the beacon frame may indicate aschedule for trigger frames (TFs) transmitted during a beacon interval.For instance, a number of TFs included in the beacon interval may beincluded in the beacon frame. In some embodiments, the beacon frame mayinclude a TF timing that may indicate a starting time or other timeassociated with one or more of the scheduled TFs. In addition, otherevents may be indicated by the beacon frame, such as transmission of ACKmessages and periods of time in which HEW stations 104 may transmit. Thebeacon frame may further include a beacon interval type that indicateswhether random access is supported by the HEW AP during the beaconinterval. In addition, random access or scheduled access may beindicated in the beacon frame for one or more of the TFs.

In some embodiments, the beacon frame may be received from the HEW AP102 in channel resources that include multiple sub-channels. Aspreviously described, the sub-channels may comprise a predeterminedbandwidth and may further comprise multiple sub-carriers. As an example,the channel resources may include four channels of 20 MHz and eachchannel may include nine sub-channels of 2.03125 MHz. Accordingly, thechannel resources may include 36 sub-channels, which may be numbered inthe range {0, 1, . . . , 35}. This example is not limiting, however, asother suitable values may be used for the bandwidth of the channelresources, channels, and sub-channels and for the number of channels andsub-channels.

At operation 310, the HEW station 104 may refrain from reception ofsignals during a sleep period between the reception of the beacon frameand the reception of a TF, which may be the earliest scheduled TF of thebeacon interval. Though not limited as such, the HEW station 104 mayalso refrain from transmission of signals and may reduce itsfunctionality and power usage during the sleep period, in some cases. Insome embodiments, the sleep period may be based at least partly on theTF timing indicated in the beacon frame. For instance, the HEW station104 may determine when the earliest TF of the beacon interval isscheduled, and may decide to enter the sleep mode for a portion of thetime period between the beacon frame and the earliest TF.

At operation 315, the HEW station 104 may receive a TF that indicates arandom access portion of the sub-channels that are allocated for randomaccess contention during an uplink transmission period. The TF may be arandom access TF, a scheduled access TF, or another type of TF. As anexample, the TF may also include allocations of dedicated sub-channelsfor scheduled transmissions by one or more associated HEW stations 104.The TF may be received from the HEW AP 102 according to the TF timingindicated in the beacon frame, in some cases.

In some embodiments, the random access portion may be indicated by arandom access Association Identifier (AID). That is, a particular AIDmay be reserved for communication of the random access portion to theHEW stations 104. For instance, a value of 0 for the AID (AID-0) may bereserved for this purpose. Information may be included in the beaconframe along with AID-0, and the HEW stations 104 may use the informationto identify which sub-channels are included in the random accessportion. It should be noted that the value of 0 is a non-limitingexample, and other suitable values may be used.

The HEW station 104 may determine a candidate sub-channel from thechannel resources, for potential use in an uplink transmission. In someembodiments, the determination may include a random selection of thecandidate sub-channel from the channel resources. The random selectionmay include uniform selection in which each of the unused sub-channelsis selected with equal probability. For instance, when 36 sub-channelsare included in the channel resources, each may be selected with aprobability of 1/36.

At operation 320, when the candidate sub-channel is included in therandom access portion indicated in the beacon frame, the HEW station 104may transmit an association request (AR) frame or other uplink frame onthe candidate sub-channel during the uplink transmission period. Thatis, a comparison between the candidate sub-channel and the allocatedgroup of random access sub-channels may be performed. It should be notedthat the other uplink frames may include a probe request (PR) frame orother management, control or action frame.

At operation 325, the HEW station 104 may refrain from transmission ofthe AR frame or other uplink frame when the candidate sub-channel isexcluded from the random access portion. In this case, the HEW station104 may wait until a second, subsequent uplink transmission period orother period to attempt random access again. At operation 330, a secondTF may be received, which may indicate a second random access portion ora second group of sub-channels allocated for random access during asecond uplink transmission period. The sub-channels may or may not bethe same as the group of sub-channels indicated in the first TF for thefirst uplink transmission period.

The HEW station 104 may select a second candidate sub-channel from thechannel resources using previously described or other techniques. Thesecond candidate sub-channel may be compared to the sub-channels in thesecond random access portion to determine whether the HEW station 104may transmit the AR frame or other uplink frame in the second uplinktransmission period. When the second candidate sub-channel is includedin the second random access portion, the HEW station 104 may transmitthe AR frame or other uplink frame on the second candidate sub-channelduring the second uplink transmission period at operation 335.

It should be noted that additional attempts for subsequent random accessperiods may be made by the HEW station 104 when the second candidatesub-channel is not part of the second random access portion. Embodimentsare not limited to just the first and second uplink transmissionperiods, and any suitable number may be used.

In addition, a low power HEW station 104 may also perform random accessusing similar techniques. At operation 340, the low power HEW station104 may transmit a diversity version of the AR frame or other uplinkframe during the second, subsequent uplink transmission period. As anexample, the low power HEW station 104 may transmit the AR frame and adiversity version of the AR frame during the first and second uplinktransmission periods described, and may use similar techniques forselection of the candidate sub-channels and comparisons with theallocated random access portions.

Operations such as 320-340 may be part of a random sub-channel back-offprocess, and may be performed when the HEW station 104 operates in anunassociated state of connectivity to the HEW AP 102. In addition, suchoperations may be performed when the beacon interval type indicatessupport for random access during the beacon interval.

The HEW station 104 may also operate in an associated state ofconnectivity to the HEW AP 102. This state may be reached, in somecases, after a successful random access by the HEW station 104. The HEWstation 104 may receive one or more TFs for random access and/orscheduled access, which may include one or more sub-channels that areallocated for dedicated transmission by the HEW station 104 during theuplink transmission period. Accordingly, a resource request (RR) framemay be transmitted by the HEW station 104 at operation 345. Embodimentsare not limited to RR frames, however, as other uplink frames may beused in some cases, including other management, control or actionframes.

In some embodiments, the TFs may include TF counters that indicate anindex of the TF with respect to the number of TFs included in the beaconinterval. The TF counter may be set to the number of TFs in the first(earliest) TF, and each subsequent TF may decrement the counter by one.That is, the TF counter may provide a “count-down” of the TF frames inthe beacon interval.

The beacon type indicator may indicate support for random access duringthe beacon interval. In addition, a “beacon phase” may also beindicated, and the HEW station 104 may use this information to determineif it can communicate and/or perform random access during the beaconinterval. As an example, an unassociated HEW station 104 may attempt toperform random access during an unassociated random access phase(U-RAP). An associated HEW station 104 may attempt to communicate duringa scheduled access phase (SAP). A low power HEW station 104 may attemptto communicate during a low-power random access phase (PS-RAP). As anexample, values of 00, 01, 10, 11 for the beacon interval type indicatormay correspond to U-RAP, PS-RAP, SAP with short packets, and SAP withlong packets, respectively.

The beacon type indicator or other parameter included in the beaconframe may indicate support for a mixture of one or more beacon phasesduring the beacon interval, an example of which will be presented below.Accordingly, multiple TFs may be received during the beacon interval,and the TFs received may include one or more random access TFs,scheduled access TFs, or mixed TFs. Although not limited as such, therandom access TFs may exclude information for associated HEW stations104 and the scheduled access TFs may exclude information forunassociated HEW stations 104. The mixed TFs may include information forboth associated and unassociated HEW stations 104.

During a beacon interval that supports such a mixture of beacon phases,the TF timing included in the beacon frame may indicate timing for one,some, or all of these TFs. Accordingly, the HEW station 104 may enter asleep mode based on the indicated timing for the appropriate TF. Forinstance, an unassociated HEW station 104 may enter the sleep mode untila TF intended for random access is scheduled.

In some embodiments, the transmission of uplink frames during the PS-RAPphase may be restricted to unassociated low power HEW stations 104. TheHEW stations 104 that are not low power HEW stations 104 may refrainfrom performing random access during the PS-RAP phase. As such, aseparate random access phase may be dedicated to the low power HEWstations 104. As an example, uplink frames (or packets) transmitted inthe PS-RAP phase may be shorter than similar uplink frames transmittedas part of the U-RAP phase. As another example, fragments of datapackets may be transmitted by the HEW stations 104 in the PS-RAP phase.As another example, multiple diversity versions of a frame or packet maybe transmitted by the HEW stations 104 in the PS-RAP phase.

Several example scenarios and configurations will be presented below forillustration of concepts. It should be noted that the examples are notlimiting. Embodiments may include some, none, or all of the featuresshown in one or more of the examples, and some embodiments may alsoinclude additional features not shown in the examples.

FIG. 4 illustrates an example of a random access scenario that includesmultiple HEW stations in accordance with some embodiments. It should benoted that embodiments are not limited to the number of HEW stations104, trigger frames (TFs) or other frames shown in FIG. 4. Embodimentsare also not limited to the example frame types shown, as other types ofuplink frames and/or downlink frames may also be used in some cases. Thebeacon frame 420 may be transmitted by the HEW AP 102 in order toprovide HEW stations 104 with information about trigger frames (TFs)scheduled for transmission by the HEW AP 102 during a beacon interval.The beacon interval may also be referred to as a beacon window or beaconperiod. In some embodiments, the beacon 420 may include a Trigger FrameSchedule Information Element (IE) 410, and may also include other IEs,parameters, data, control information or other information not shown inFIG. 4.

The Trigger Frame Schedule IE 410 is shown in more detail at the top ofFIG. 4, and may include any or all of an element ID 411, a length 412, anumber of TFs 413 included in the beacon interval, and a TF start time414. It should be noted that the Trigger Frame Schedule IE 410 may alsoinclude other parameters, data, control information or other informationnot shown in FIG. 4. In addition, the Trigger Frame Schedule IE 410 isalso not limited to the order or presentation of the parameters 411-414as shown in FIG. 4.

The first TF 430 may be transmitted for reception at the HEW stations104. As shown in FIG. 4, a duration of time between the transmissions ofthe beacon 420 and the first TF 430 may be the TF start time 425. Theduration may also be considered a “doze time” 426 from the perspectiveof the HEW stations 104. Accordingly, the HEW stations 104 may enter asleep mode or a mode of reduced operation after decoding the beacon 420and before the reception of the first TF 430. As previously described,the TF 430 may indicate sub-channel allocations for one or moreassociated stations, such as HEW stations #1 and #2 in this example. TheTF 430 may also indicate a group of available random access sub-channelsallocated for random access by unassociated stations, such as HEWstations #3 and #4 in this example.

When a short inter-frame space (SIFS) 435 has elapsed since thereception of the TF 430, the HEW stations 104 may transmit anassociation request (AR) or a resource request (RR). In the example ofFIG. 4, HEW stations #1 and #2 are both associated with the HEW AP 102,and therefore they transmit the RRs 460, 470. The unassociated HEWstation #3 transmits the AR 480, while the unassociated HEW station #4does not transmit an AR. As an example, HEW station #4 may have randomlyselected an AR transmission sub-channel that is not part of the group ofavailable random access sub-channels specified in the TF 430.Accordingly, the HEW station #4 may be restricted or prohibited from ARtransmission during the time period after the SIFS 435.

An ACK message 440 may be transmitted by the HEW AP 102, and may providefeedback (e.g. decoding success or failure) related to the reception ofthe RRs 460, 470, the AR 480, and perhaps other frames. The ACK 440 mayinclude any number of individual ACKs 441-443 in some cases.

The second TF 450 may be transmitted for reception at the HEW stations104. As an example, the transmission of the second TF 450 may occurafter a predetermined spacing has elapsed since the transmission of thefirst TF 430. As another example, the transmission of the second TF 450may occur at a time indicated in the beacon 420 or in the first TF 430.These examples are not limiting, however, and any suitable technique fordetermination of the transmission time for the second TF 450 may beused.

As previously described, the TF 450 may indicate sub-channel allocationsfor one or more associated stations. The TF 450 may also indicate agroup of available random access sub-channels allocated for randomaccess, and the group may or may not be the same as the group specifiedin the TF 430. In this case, HEW station #4 may have randomly selectedan AR transmission sub-channel that is part of the group of availablerandom access sub-channels specified in the TF 450. The HEW station #4may therefore transmit the AR 490 when the SIFS 455 has elapsed afterthe reception of the second TF 450.

In addition, the TFs 430, 450 may include a TF counter that indicates anindex of the random access TF with respect to the number of TFs includedin the beacon interval. For instance, the TF counter may provide a“count-down” of the TF frames in the beacon interval. The TF countervalue included in the first TF 430 may be initialized to the number ofTFs in the beacon interval. The TF counter may be decremented by one forthe second TF 450, and may be further decremented by one during eachsubsequent TF in the beacon interval. As an example, the TF counter mayenable unassociated HEW stations 104 to set a network allocation vector(NAV) according to the end of the last scheduled TF in the beaconinterval.

FIG. 5 illustrates an example of another random access scenario thatincludes multiple HEW stations in accordance with some embodiments. Inthe example scenario 500, a beacon phase (or beacon interval type) forthe beacon interval is set to the value of uplink random access phase(U-RAP). As a non-limiting example, a value of 00 for the beaconinterval type may indicate U-RAP operation for the beacon interval. Forthe U-RAP operation, uplink frames may be transmitted by unassociatedHEW stations 104. In some embodiments, the transmission of uplink framesmay be restricted to unassociated HEW stations 104, and related TFs mayexclude allocations for associated HEW stations 104. In someembodiments, a range of resource units (RUs) or sub-channels may berestricted by the HEW AP 102 for the U-RAP operation. It should be notedthat embodiments are not limited to the number of HEW stations 104,trigger frames (TFs) or other frames shown in FIG. 5.

The beacon frame 510 may be transmitted by the HEW AP 102 in order toprovide HEW stations 104 with information about trigger frames (TFs)scheduled for transmission by the HEW AP 102 during a beacon interval.The beacon interval may also be referred to as a beacon window or beaconperiod. In some embodiments, the beacon 510 may include a Trigger FrameSchedule Information Element (IE) 410, and may also include other IEs,parameters, data, control information or other information about thebeacon interval.

The CTS-to-self frame 530 may be transmitted for reception at the HEWstations 104. In some cases, a TF may be transmitted instead of theCTS-to-self frame 530. As shown in FIG. 5, a duration of time betweenthe transmissions of the beacon 510 and the CTS-to-self frame 530 may bethe U-RAP start time 525. In some embodiments, the U-RAP start time 525may be indicated in the beacon 510. The CTS-to-self frame 530 mayindicate a group of available random access sub-channels allocated forrandom access by unassociated stations, such as HEW stations #1, #2, and#3.

When a short inter-frame space (SIFS) 535 has elapsed since thereception of the CTS-to-self frame 530, the HEW stations 104 maytransmit a management frame, such as an association request (AR) or aprobe request (PR), as indicated by 541-543. An ACK message 550 (shownas a multi-user block ACK (MU-BA) in FIG. 5) may be transmitted by theHEW AP 102, and may provide feedback (e.g. decoding success or failure)related to the reception of the AR/PRs 541-543. Although not limited assuch, the ACK message 550 may be transmitted after the SIFS 545 haselapsed since the reception of the AR/PRs 541-543. As an example, theU-RAP interval 560 may reflect a time duration between the CTS-to-selfframe 530 and the MU-BA 550. This example is not limiting, however, asthe U-RAP interval may reflect other time durations related to elapsedtimes between other frames, in some cases.

FIG. 6 illustrates an example of another random access scenario thatincludes multiple HEW stations in accordance with some embodiments. Inthe example scenario 600, a beacon phase (or beacon interval type) forthe beacon interval is set to the value of low power random access phase(PS-RAP). As a non-limiting example, a value of 01 for the beaconinterval type may indicate PS-RAP operation for the beacon interval. Aspreviously described, for the PS-RAP operation, uplink frames may betransmitted by low power HEW stations 104. It should be noted thatembodiments are not limited to the number of HEW stations 104, triggerframes (TFs) or other frames shown in FIG. 6.

As previously described, the beacon frame 610 may provide HEW stations104 with information about trigger frames (TFs) scheduled fortransmission by the HEW AP 102 during a beacon interval. The CTS-to-selfframe 630 may be transmitted for reception at the HEW stations 104, anda TF may be transmitted instead of the CTS-to-self frame 630 in somecases. A duration of time between the transmissions of the beacon 610and the CTS-to-self frame 630 may be the PS-RAP start time 625, whichmay be indicated in the beacon 610 in some cases. The CTS-to-self frame630 may indicate a group of available random access sub-channelsallocated for random access by unassociated low power stations, resourceallocations for one or more associated low power HEW stations 104, or acombination thereof.

When an SIFS 635 has elapsed since the reception of the CTS-to-selfframe 630, the HEW stations 104 may transmit a data fragment 641-643 orother frame or packet. A TF 650 may be transmitted after the SIFS 645has elapsed since the transmission of the data fragments 641-643. EachHEW station 104 may transmit an Aggregated MAC PDU (A-MPDU) 661-663 orother fragment, frame, or packet after the SIFS 655 has elapsed. The HEWAP 102 may transmit the MU-BA 670, which may provide feedback (e.g.decoding success or failure) related to the reception of the datafragments 641-643 and/or the A-MPDUs 661-663. Although not limited assuch, the MU-BA 670 may be transmitted after the SIFS 665 has elapsedsince the reception of the A-MPDUs 661-663. As an example, the PS-RAPinterval 680 may reflect a time duration between the CTS-to-self frame630 and the MU-BA 670. This example is not limiting, however, as thePS-RAP interval may reflect other time durations related to elapsedtimes between other frames, in some cases.

FIG. 7 illustrates an example of another random access scenario thatincludes multiple HEW stations in accordance with some embodiments. Inthe example scenario 700, a beacon phase (or beacon interval type) forthe beacon interval is set to the value of scheduled access phase (SAP).As a non-limiting example, a value of 10 for the beacon interval typemay indicate SAP operation with short packets while a value of 11 forthe beacon interval type may indicate SAP operation with long packets.As previously described, for the SAP operation, uplink frames may betransmitted by each HEW station 104 on one or more sub-channels orresources dedicated to the HEW station 104. It should be noted thatembodiments are not limited to the number of HEW stations 104, triggerframes (TFs) or other frames shown in FIG. 7.

As previously described, the beacon frame 710 may provide HEW stations104 with information about trigger frames (TFs) scheduled fortransmission by the HEW AP 102 during a beacon interval. The CTS-to-selfframe 730 may be transmitted for reception at the HEW stations 104, anda TF may be transmitted instead of the CTS-to-self frame 730 in somecases. A duration of time between the transmissions of the beacon 710and the CTS-to-self frame 730 may be the SAP start time 725, which maybe indicated in the beacon 710 in some cases. The CTS-to-self frame 730may indicate resource allocations for associated HEW stations 104, suchas HEW stations #1 and #2.

When an SIFS 735 has elapsed since the reception of the CTS-to-selfframe 730, the HEW stations 104 may transmit an A-MPDU 741, 742 or otherframe or packet on the allocated sub-channels. The HEW AP 102 maytransmit the MU-BA 750, which may provide feedback (e.g. decodingsuccess or failure) related to the reception of the A-MPDUs 741, 742.Although not limited as such, the MU-BA 750 may be transmitted after theSIFS 745 has elapsed since the reception of the A-MPDUs 741, 742. As anexample, the SAP interval 740 may reflect a time duration between theCTS-to-self frame 730 and the MU-BA 750. This example is not limiting,however, as the SAP interval may reflect other time durations related toelapsed times between other frames, in some cases.

FIG. 8 illustrates an example of another random access scenario thatincludes multiple random access phases in accordance with someembodiments. In the example scenario 800, a beacon interval supports amixture of beacon phases that includes the U-RAP 820, the SAP 830, andthe PS-RAP 840. It should be noted that embodiments are not limited tothe order of the phases shown in FIG. 8 or to the number of phasesshown.

The beacon frame 810 may be transmitted by the HEW AP 102, and mayindicate or include timing for each of the phases 820, 830, 840. Thetime durations 825, 835, 845 may be related to the U-RAP interval, SAPinterval, and PS-RAP interval previously described, though not limitedas such. Various HEW stations 104 may select to communicate with the HEWAP 102 during an appropriate phase of the beacon interval. Anunassociated HEW station 104 may attempt to communicate during the U-RAPphase 820. An associated HEW station 104 may attempt to communicateduring the SAP phase 830. A low power HEW station 104 may attempt tocommunicate during the PS-RAP phase 840. As an example, an associatedHEW station 104 communicating during the SAP phase 830 may enter a sleepmode between the time of the beacon transmission and a starting time orother time associated with the SAP phase 830. Embodiments may includetechniques previously described regarding the different phases and/orthe scenarios 400, 500, 600, and 700 shown in FIGS. 4-7, but are notlimited as such.

FIG. 9 illustrates the operation of another method of random accesscontention in accordance with some embodiments. As mentioned previouslyregarding the method 300, embodiments of the method 900 may includeadditional or even fewer operations or processes in comparison to whatis illustrated in FIG. 9 and embodiments of the method 900 are notnecessarily limited to the chronological order that is shown in FIG. 9.In describing the method 900, reference may be made to FIGS. 1-8,although it is understood that the method 900 may be practiced with anyother suitable systems, interfaces and components. In addition,embodiments of the method 600 may refer to eNBs 104, UEs 102, APs, STAsor other wireless or mobile devices.

It should be noted that the method 900 may be practiced at an HEW AP102, and may include exchanging of signals or messages with an HEWstation 104. Similarly, the method 300 may be practiced at the HEWstation 104, and may include exchanging of signals or messages with theHEW AP 102. In some cases, operations and techniques described as partof the method 300 may be relevant to the method 900. In addition,embodiments may include operations performed at the HEW AP 102 that arereciprocal or similar to other operations described herein performed atthe HEW station 104. For instance, an operation of the method 900 mayinclude transmission of a frame by the AP 102 while an operation of themethod 300 may include reception of the same frame or similar frame bythe HEW station 104.

In addition, previous discussion of various techniques and concepts maybe applicable to the method 900 in some cases, including the beaconframe, beacon interval, beacon phase, and trigger frame (TF). Otherconcepts previously described, such as the access request (AR), proberequest (PR), resource request (RR), channel resources, sub-channels,and sub-carriers may also be applicable to the method 900. In addition,the example scenarios shown in FIGS. 4-8 may also be applicable, in somecases.

At operation 905, the HEW AP 102 may transmit a beacon frame thatindicates a schedule of events for a beacon interval. The events mayinclude transmission of TFs by the HEW AP 102, reception of uplinkframes from one or more HEW stations 104, transmission of other frames,and/or reception of other frames. The beacon frame may includeadditional information and parameters, as previously described.

At operation 910, a first random TF may be transmitted, and may indicatea first random access portion of channel resources allocated for randomaccess by the HEW stations 104 during a first random access period. Oneor more AR frames or other uplink frames may be received from the HEWstations 104 in the first random access portion during the first randomaccess period at operation 915. The received uplink frames may includeone or more association request (AR) frames, probe request (PR) framesor other uplink frames. For instance, the uplink frames may be or mayinclude management, control or action frames.

At operation 920, a second random access TF that indicates a secondrandom access portion of the channel resources for a second randomaccess period may be transmitted. The second channel resources may bebased at least partly on the received uplink frames. For instance, thenumber of AR frames or other uplink frames successfully decoded duringthe first random access period may influence the HEW AP 102 to allocatemore dedicated sub-channels and fewer random access sub-channels for thesecond random access period. At operation 925, one or more AR frames orother uplink frames may be received from the HEW stations 104 in thesecond random access portion during the second random access period.

At operation 930, a first scheduled access TF may be transmitted and mayindicate a dedicated access portion of the channel resources allocatedto a first HEW station 104 during a first scheduled access period. Atoperation 935, one or more RR frames or other frames may be receivedfrom the first HEW station 104 in the dedicated access portion duringthe first scheduled access period. Embodiments are not limited to justthe first HEW station for the scheduled access TF.

An example of a high-efficiency Wi-Fi (HEW) station is disclosed herein.The HEW station may comprise hardware processing circuitry configured toreceive a beacon frame that indicates a trigger frame (TF) timing for abeacon interval. The beacon frame may be received from an HEW accesspoint (AP) in channel resources that include multiple sub-channels. Thehardware processing circuitry may be further configured to receive arandom access TF that indicates a random access portion of thesub-channels that are allocated for random access contention during anuplink transmission period. The hardware processing circuitry may befurther configured to determine a candidate sub-channel from the channelresources. The hardware processing circuitry may be further configuredto, when the candidate sub-channel is included in the random accessportion, transmit an uplink frame on the candidate sub-channel duringthe uplink transmission period.

In some examples, the beacon frame may further indicate a number of TFsincluded in the beacon interval. The random access TF may be receivedfrom the HEW AP according to the indicated TF timing. In some examples,the random access portion may be indicated by a random accessAssociation Identifier (AID). In some examples, the uplink frame mayinclude an association request (AR) frame or a probe request (PR) frame.In some examples, the candidate sub-channel may be selected randomlyfrom the channel resources. In some examples, the hardware processingcircuitry may be further configured to refrain from transmission of theuplink frame when the candidate sub-channel is excluded from the randomaccess portion.

In some examples, the hardware processing circuitry may be furtherconfigured to, when the candidate sub-channel is excluded from therandom access portion, receive a second, subsequent random access TFthat indicates a second random access portion of the sub-channels for asecond uplink transmission period. The hardware processing circuitry maybe further configured to, when the candidate sub-channel is excludedfrom the random access portion, randomly select a second candidatesub-channel from the channel resources and transmit the uplink frame onthe second candidate sub-channel during the second uplink transmissionperiod when the second candidate sub-channel is included in the secondrandom access portion.

In some examples, the determination of the candidate sub-channel and thetransmission of the uplink frame may be performed when the HEW stationoperates in an unassociated state of connectivity to the HEW AP. In someexamples, the hardware processing circuitry may be further configuredto, when the HEW station operates in an associated state of connectivityto the HEW AP, determine one or sub-channels that are allocated fortransmission by the HEW station during the uplink transmission period.The determination may be based at least partly on the random access TF.The hardware processing circuitry may be further configured to, when theHEW station operates in the associated state of connectivity to the HEWAP, transmit a resource request (RR) frame on the allocated sub-channelsduring the uplink transmission period.

In some examples, the hardware processing circuitry may be furtherconfigured to refrain from reception of signals during a sleep periodbetween the reception of the beacon frame and the reception of therandom access TF. The sleep period may be based at least partly on theTF timing indicated in the beacon frame. In some examples, the hardwareprocessing circuitry may be further configured to receive a second,subsequent random access TF. Each of the random access TFs may include aTF counter that indicates an index of the random access TF with respectto the number of TFs included in the beacon interval.

In some examples, the beacon frame may further include a beacon intervaltype that indicates whether random access is supported by the HEW APduring the beacon interval. The reception of the random access TF, thedetermination of the candidate sub-channel, and the transmission of theuplink frame may be performed when the beacon interval type indicatessupport for random access.

In some examples, the support for random access may be indicated byvalues of unassociated random access phase (U-RAP) or low power randomaccess phase (PS-RAP) for the beacon interval type. When the beaconinterval type takes the PS-RAP value, the beacon interval may beintended for low power HEW stations and the hardware processingcircuitry may be further configured to transmit a diversity version ofthe uplink frame during a second, subsequent uplink transmission period.

In some examples, when the beacon interval type indicates support forboth random access and scheduled access, the hardware processingcircuitry may be further configured to receive one or more additionalTFs, and the random access TF may be intended for HEW stations operatingin the unassociated state of connectivity to the HEW AP. Furthermore,when the beacon interval type indicates support for both random accessand scheduled access, at least one of the additional TFs may excludeallocations of sub-channels for random access and may includeallocations of sub-channels for dedicated transmissions by HEW stationsoperating in an associated state of connectivity to the HEW AP, and theTF timing included in the beacon frame may indicate timing for therandom access TF and the additional TFs.

In some examples, the random access TF may further indicate a scheduledaccess portion of the sub-channels that are allocated to a second HEWstation for the uplink transmission period. In some examples, thesub-channels may comprise a predetermined bandwidth and may furthercomprise multiple sub-carriers. In some examples, the HEW station mayfurther comprise one or more antennas configured to receive the beaconframe and the random access TF and to transmit the uplink frame.

An example method for uplink random access contention performed by ahigh-efficiency Wi-Fi (HEW) station is also disclosed herein. The methodmay comprise receiving a beacon frame that indicates a schedule fortrigger frames (TFs) transmitted by an HEW access point (AP) during abeacon interval and further indicates either random access or scheduledaccess for the TFs. The method may further comprise, when the HEWstation operates in an unassociated state of connectivity to the HEW AP,refraining from reception of signals during a sleep period between thebeacon frame and a random access TF. The method may further comprise,when the HEW station operates in the unassociated state, transmitting anuplink frame on a randomly selected sub-channel when the randomlyselected sub-channel is included in a random access portion of channelresources indicated in the random access TF.

In some examples, the method may further comprise, when the HEW stationoperates in an associated state of connectivity to the HEW AP,refraining from reception of signals during a sleep period between thebeacon frame and a scheduled access TF. The method may further comprise,when the HEW station operates in the associated state, transmitting aresource request (RR) frame in a portion of the channel resourcesdedicated to the HEW station and indicated in the scheduled access TF.

In some examples, the beacon frame may further indicate a TF timing forthe random access TF and the scheduled access TF, and the sleep periodsmay be based on the TF timing. In some examples, at least one of thescheduled TFs may be for an unassociated random access phase (U-RAP)portion of the beacon interval, the U-RAP portion reserved for HEWstations operating in an unassociated state of connectivity to the HEWAP. At least one of the scheduled TFs may be for a low-power randomaccess phase (PS-RAP) portion of the beacon interval, the PS-RAP portionreserved for low power HEW stations operating in the unassociated state.At least one of the scheduled TFs may be for a scheduled access phase(SAP) portion of the beacon interval, the SAP portion reserved for HEWstations operating in an associated state of connectivity to the HEW AP.

In some examples, the channel resources may comprise multiplesub-channels. The sub-channels may comprise a predetermined bandwidthand may further comprise multiple sub-carriers.

An example of a non-transitory computer-readable storage medium thatstores instructions for execution by one or more processors of ahigh-efficiency WiFi (HEW) station to perform operations forcommunication is also disclosed herein. The operations may configure theone or more processors to receive a beacon frame that indicates a numberof trigger frames (TFs) included in a beacon interval and furtherindicates a TF timing for the beacon frame. The beacon frame may bereceived from an HEW access point (AP) in channel resources that includemultiple sub-channels. The operations may further configure the one ormore processors to receive a random access TF that indicates a randomaccess portion of the sub-channels that are allocated for random accesscontention during an uplink transmission period. The random access TFmay be received from the HEW AP according to the indicated TF timing.The operations may further configure the one or more processors todetermine a candidate sub-channel from the channel resources and, whenthe candidate sub-channel is included in the random access portion,transmit an uplink frame on the candidate sub-channel during the uplinktransmission period. In some examples, the operations may furtherconfigure the one or more processors to refrain from transmission of theuplink frame when the candidate sub-channel is excluded from the randomaccess portion.

An example of a high-efficiency Wi-Fi (HEW) access point (AP) is alsodisclosed herein. The HEW AP may comprise hardware processing circuitryconfigured to transmit a beacon frame that indicates a schedule ofevents for a beacon interval, wherein the events include transmission ofTFs by the HEW AP and reception of uplink frames from one or more HEWstations. The hardware processing circuitry may be further configured totransmit a first random access TF that indicates a first random accessportion of channel resources allocated for random access by the HEWstations during a first random access period. The hardware processingcircuitry may be further configured to receive one or more accessrequest (AR) frames from the HEW stations in the first random accessportion during the first random access period. The hardware processingcircuitry may be further configured to transmit a second random accessTF that indicates a second random access portion of the channelresources for a second random access period. The second random accessportion may be based at least partly on the received AR frames.

In some examples, the hardware processing circuitry may be furtherconfigured to transmit a first scheduled access TF that indicates adedicated access portion of the channel resources allocated to a firstHEW station during a first scheduled access period. The hardwareprocessing circuitry may be further configured to receive one or moreresource request (RR) frames from the first HEW station in the dedicatedaccess portion during the first scheduled access period. In someexamples, the HEW AP may further comprise one or more antennasconfigured to transmit the beacon frames and the TFs and to receive theAR frames and the RR frames.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

What is claimed is:
 1. A high-efficiency (HE) station comprising:memory; and, hardware processing circuitry coupled to the memory, thehardware processing circuitry configured to: receive a beacon frame thatindicates a trigger frame (TF) timing for a beacon interval, wherein thebeacon frame is received from an HE access point (AP) in channelresources that include multiple sub-channels; receive a random access TFthat indicates a random access portion of the sub-channels that areallocated for random access contention during an uplink transmissionperiod; determine a candidate sub-channel from the channel resources;when the candidate sub-channel is included in the random access portion,transmit an uplink frame on the candidate sub-channel during the uplinktransmission period; refrain from transmission of the uplink frame whenthe candidate sub-channel is excluded from the random access portion;and when the candidate sub-channel is excluded from the random accessportion: receive a second, subsequent random access TF that indicates asecond random access portion of the sub-channels for a second uplinktransmission period, select a second candidate sub-channel from thechannel resources, and transmit the uplink frame on the second candidatesub-channel during the second uplink transmission period when the secondcandidate sub-channel is included in the second random access portion.2. The HE station according to claim 1, wherein the beacon frame furtherindicates a number of TFs included in the beacon interval, and whereinthe random access TF is received from the HEW AP according to theindicated TF timing.
 3. The HE station according to claim 1, wherein therandom access portion is indicated by a random access AssociationIdentifier (AID).
 4. The HE station according to claim 1, wherein theuplink frame includes an association request (AR) frame or a proberequest (PR) frame.
 5. The HE station according to claim 1, wherein thecandidate sub-channel is selected randomly from the channel resources.6. The HE station according to claim 1, wherein the determination of thecandidate sub-channel and the transmission of the uplink frame areperformed when the HEW station operates in an unassociated state ofconnectivity to the HEW AP.
 7. The HE station according to claim 6, thehardware processing circuitry further configured to: when the HEWstation operates in an associated state of connectivity to the HEW AP:determine, based at least partly on the random access TF, one orsub-channels that are allocated for transmission by the HEW stationduring the uplink transmission period; and transmit a resource request(RR) frame on the allocated sub-channels during the uplink transmissionperiod.
 8. The HE station according to claim 1, wherein: the hardwareprocessing circuitry is further configured to refrain from reception ofsignals during a sleep period between the reception of the beacon frameand the reception of the random access TF, and the sleep period is basedat least partly on the TF timing indicated in the beacon frame.
 9. TheHE station according to claim 1, wherein: the hardware processingcircuitry is further configured to receive a second, subsequent randomaccess TF, and each of the random access TFs includes a TF counter thatindicates an index of the random access TF with respect to the number ofTFs included in the beacon interval.
 10. The HE station according toclaim 1, wherein: the beacon frame further includes a beacon intervaltype that indicates whether random access is supported by the HEW APduring the beacon interval, the reception of the random access TF, thedetermination of the candidate sub-channel, and the transmission of theuplink frame are performed when the beacon interval type indicatessupport for random access.
 11. The HE station according to claim 10,wherein: the support for random access is indicated by values ofunassociated random access phase (U-RAP) or low power random accessphase (PS-RAP) for the beacon interval type, and when the beaconinterval type takes the PS-RAP value: the beacon interval is intendedfor low power HEW stations, and the hardware processing circuitry isfurther configured to transmit a diversity version of the uplink frameduring a second, subsequent uplink transmission period.
 12. The HEstation according to claim 10, wherein: when the beacon interval typeindicates support for both random access and scheduled access: thehardware processing circuitry is further configured to receive one ormore additional TFs, the random access TF is intended for HEW stationsoperating in the unassociated state of connectivity to the HEW AP, atleast one of the additional TFs excludes allocations of sub-channels forrandom access and includes allocations of sub-channels for dedicatedtransmissions by HEW stations operating in an associated state ofconnectivity to the HEW AP, and the TF timing included in the beaconframe indicates timing for the random access TF and the additional TFs.13. The HE station according to claim 1, wherein the random access TFfurther indicates a scheduled access portion of the sub-channels thatare allocated to a second HEW station for the uplink transmissionperiod.
 14. The HE station according to claim 1, wherein thesub-channels comprise a predetermined bandwidth and further comprisemultiple sub-carriers.
 15. The HE station according to claim 1, the HEWstation further comprising one or more antennas configured to receivethe beacon frame and the random access TF and to transmit the uplinkframe.
 16. A method for uplink random access contention performed by ahigh-efficiency (HE) station, the method comprising: receiving a beaconframe that indicates a schedule for trigger frames (TFs) transmitted byan HE access point (AP) during a beacon interval and further indicateseither random access or scheduled access for the TFs; when the HEWstation operates in an unassociated state of connect to the HEW AP:refraining from reception of signals during a sleep period between thebeacon frame and a random access TF; and transmitting an uplink frame ona randomly selected sub-channel when the randomly selected sub-channelis included in a random access portion of channel resources indicated inthe random access TF, wherein at least one of the scheduled TFs is foran unassociated random access phase (U-RAP) portion of the beaconinterval, the U-RAP portion reserved for HE stations operating in anunassociated state of connectivity to the HE AP, at least one of thescheduled TFs is for a low-power random access phase (PS-RAP) portion ofthe beacon interval, the PS-RAP portion reserved for low power HEstations operating in the unassociated state, and at least one of thescheduled TFs is for a scheduled access phase (SAP) portion of thebeacon interval, the SAP portion reserved for HE stations operating inan associated state of connectivity to the HE AP.
 17. The methodaccording to claim 16, the method further comprising: when the HEstation operates in an associated state of connectivity to the HEW AP:refraining from reception of signals during a sleep period between thebeacon frame and a scheduled access TF; and transmitting a resourcerequest (RR) frame in a portion of the channel resources dedicated tothe HE station and indicated in the scheduled access TF.
 18. The methodaccording to claim 17, wherein the beacon frame further indicates a TFtiming for the random access TF and the scheduled access TF, and thesleep periods are based on the TF timing.
 19. The method according toclaim 16, wherein: the channel resources comprise multiple sub-channels,and the sub-channels comprise a predetermined bandwidth and furthercomprise multiple sub-carriers.